FIG. 1 depicts a conventional method 10 for fabricating a structure in magnetic recording technology applications. FIGS. 2-3 depict a conventional transducer 50 during fabrication using the method 10. FIGS. 2-3 are not to scale. The method 10 typically commences after the material(s) for the structure have been deposited. For example, the method 10 may be used in fabricating a conventional magnetoresistive read sensor in a read transducer. Alternatively, the conventional method 10 might be used in fabricating the pin portion of a conventional near-field transducer (NFT) in an energy assisted magnetic recording (EAMR) write transducer.
The conventional method 10 commences by providing a conventional hard mask layer, a conventional bottom antireflective coating (BARC) layer, and a photoresist mask, via step 12. The conventional BARC layer aids in patterning of the conventional photoresist mask. The conventional photoresist mask has the desired pattern. For structures such as a conventional magnetoresistive sensor or pin portion of the NFT, the photoresist mask includes a line.
The photoresist line in the conventional photoresist mask is trimmed, via step 14. Typically, an oxygen plasma reactive ion etch (RIE) or other analogous process is used to reduce the width of the photoresist line. The pattern of the photoresist mask is then transferred to the BARC layer, via step 16. Typically, step 16 is transferred to the BARC layer using an etch chemistry appropriate to the BARC layer. FIG. 2 depicts the conventional transducer 50 after step 16 is performed. The layers 52 for the device 52, hard mask 54, BARC layer 56 and photoresist mask 58 are shown. If a conventional magnetoresistive structure is to be formed, the stack of layers 52 typically includes an antiferromagnetic (AFM) layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. In addition, seed and/or capping layers may be used. The conventional layers 52 reside on an underlayer (not shown), which may be a substrate. The conventional hard mask layer 54 is typically a material such as SiC or diamond-like carbon (DLC). The BARC layer 56 is typically an organic BARC, such as AR3. Also shown is the photoresist mask 58. The line portion of the photoresist mask 58 is shown. Because step 16 has been performed, the BARC 56 has the same width as the photoresist line 58.
A conventional hard mask is defined from the hard mask layer 54, via step 18. Stated differently, the line/pattern of the conventional photoresist mask 58 and BARC 56 is transferred to the hard mask layer 54. Step 18 typically includes performing an RIE appropriate to the material used for the hard mask 54. FIG. 3 depicts the conventional transducer 50 after step 18 is carried out. Thus, the conventional hard mask 54′ has the pattern of the photoresist mask 58′ and BARC layer 56′. The hard mask 54′ thus has the same width, w, as the BARC 56′ and photoresist line 58′. As can be seen in FIG. 3, a portion of the photoresist 58′ remains after step 18 is performed.
The structure is defined, via step 20. Step 20 typically includes ion milling the transducer 50 or performing an RIE. Thus, the portion of the magnetoresistive stack or NFT layer 52 exposed is removed. The photoresist 58′ remaining after step 18 aids in performing step 20. In particular, the photoresist 58′ aids in ensuring that the desired portion of the underlying device layer(s) 52 remain covered. Some or all of the photoresist 58′ may be consumed in step 20. Fabrication of the conventional transducer 50 may then be completed.
Although the conventional method 10 allows the conventional transducer 50 to be fabricated with line widths below one hundred nanometers, there are several drawbacks. The current trend is to higher density recording and, therefore, smaller track widths. The width of the structure to be fabricated is thus desired to be reduced. To do so, the width, w, of the mask 54′, 56′, and 58′ are also desired to be decreased. For example, in some applications, the width of the structure desired to be fabricated from the hard mask 54′ may be lower than fifty nanometers. The conventional method 10 may not be capable of fabricating a line at such small widths. For example, the photoresist line 58′ is typically quite thick—on the order of 0.2 microns or more. When such a thick resist line has such a narrow width, the resist line may bend or fall during fabrication. Alternatively, the photoresist line 58′ may have a large footing. As a result, there may be large variation in the width of the structure fabricated from the layers 52 and a large wafer to wafer variation. Such variations are undesirable. Yield may also be adversely affected.
Accordingly, what is needed is a system and method for improving the fabrication of a structure in a magnetic recording transducer.